Mattress



FIG. 1 is a perspective view of a mattress showing my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is an enlarged view of the mattress taken from the circle part in FIG. 7 .

The broken lines used in FIGS. 7-8 depict enlargement boundary lines that form no part of the claimed design. 

CLAIM The ornamental design for a mattress, as shown and described. 